// SPDX-FileCopyrightText: © 2025 Tenstorrent AI ULC.
//
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//===----------------------------------------------------------------------===//
//===- llvm/ADT/SmallVector.cpp - 'Normally small' vectors ----------------===//
//
// Originally part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
// This file is a modified version of llvm/ADT/SmallVector.cpp.
// Modifications were made by Tenstorrent AI ULC. in 2025 to integrate into internal codebase.
//
//===----------------------------------------------------------------------===//
//
// This file implements the SmallVector class.
//
//===----------------------------------------------------------------------===//
// tt_stl: modified from llvm/ADT/SmallVector.cpp
// Modifications include:
// - Twine dependency removed
// - Removed report_fatal_error(Twine(Reason))
// - Added ttsl::detail:: prefix to LLVM namespace

#include "llvm_small_vector.hpp"

#include "memory_alloc.hpp"
#include <cstdint>
#include <stdexcept>

using namespace ttsl::detail::llvm;

// Check that no bytes are wasted and everything is well-aligned.
namespace {
// These structures may cause binary compat warnings on AIX. Suppress the
// warning since we are only using these types for the static assertions below.
#if defined(_AIX)
#pragma GCC diagnostic push
#pragma GCC diagnostic ignored "-Waix-compat"
#endif
struct Struct16B {
    alignas(16) void* X;
};
struct Struct32B {
    alignas(32) void* X;
};
#if defined(_AIX)
#pragma GCC diagnostic pop
#endif
}  // namespace
static_assert(
    sizeof(SmallVector<void*, 0>) == sizeof(unsigned) * 2 + sizeof(void*), "wasted space in SmallVector size 0");
static_assert(alignof(SmallVector<Struct16B, 0>) >= alignof(Struct16B), "wrong alignment for 16-byte aligned T");
static_assert(alignof(SmallVector<Struct32B, 0>) >= alignof(Struct32B), "wrong alignment for 32-byte aligned T");
static_assert(sizeof(SmallVector<Struct16B, 0>) >= alignof(Struct16B), "missing padding for 16-byte aligned T");
static_assert(sizeof(SmallVector<Struct32B, 0>) >= alignof(Struct32B), "missing padding for 32-byte aligned T");
static_assert(
    sizeof(SmallVector<void*, 1>) == sizeof(unsigned) * 2 + sizeof(void*) * 2, "wasted space in SmallVector size 1");

static_assert(
    sizeof(SmallVector<char, 0>) == sizeof(void*) * 2 + sizeof(void*),
    "1 byte elements have word-sized type for size and capacity");

namespace {
/// Report that MinSize doesn't fit into this vector's size type. Throws
/// std::length_error or calls report_fatal_error.
[[noreturn]] void report_size_overflow(size_t MinSize, size_t MaxSize) {
    std::string Reason = "SmallVector unable to grow. Requested capacity (" + std::to_string(MinSize) +
                         ") is larger than maximum value for size type (" + std::to_string(MaxSize) + ")";

    throw std::length_error(Reason);
}

/// Report that this vector is already at maximum capacity. Throws
/// std::length_error or calls report_fatal_error.
[[noreturn]] void report_at_maximum_capacity(size_t MaxSize) {
    std::string Reason = "SmallVector capacity unable to grow. Already at maximum size " + std::to_string(MaxSize);
    throw std::length_error(Reason);
}

// Note: Moving this function into the header may cause performance regression.
template <class Size_T>
size_t getNewCapacity(size_t MinSize, size_t TSize, size_t OldCapacity) {
    constexpr size_t MaxSize = std::numeric_limits<Size_T>::max();

    // Ensure we can fit the new capacity.
    // This is only going to be applicable when the capacity is 32 bit.
    if (MinSize > MaxSize) {
        report_size_overflow(MinSize, MaxSize);
    }

    // Ensure we can meet the guarantee of space for at least one more element.
    // The above check alone will not catch the case where grow is called with a
    // default MinSize of 0, but the current capacity cannot be increased.
    // This is only going to be applicable when the capacity is 32 bit.
    if (OldCapacity == MaxSize) {
        report_at_maximum_capacity(MaxSize);
    }

    // In theory 2*capacity can overflow if the capacity is 64 bit, but the
    // original capacity would never be large enough for this to be a problem.
    size_t NewCapacity = (2 * OldCapacity) + 1;  // Always grow.
    return std::clamp(NewCapacity, MinSize, MaxSize);
}

/// If vector was first created with capacity 0, getFirstEl() points to the
/// memory right after, an area unallocated. If a subsequent allocation,
/// that grows the vector, happens to return the same pointer as getFirstEl(),
/// get a new allocation, otherwise isSmall() will falsely return that no
/// allocation was done (true) and the memory will not be freed in the
/// destructor. If a VSize is given (vector size), also copy that many
/// elements to the new allocation - used if realloca fails to increase
/// space, and happens to allocate precisely at BeginX.
/// This is unlikely to be called often, but resolves a memory leak when the
/// situation does occur.
void* replaceAllocation(void* NewElts, size_t TSize, size_t NewCapacity, size_t VSize = 0) {
    void* NewEltsReplace = safe_malloc(NewCapacity * TSize);
    if (VSize) {
        memcpy(NewEltsReplace, NewElts, VSize * TSize);
    }
    // NOLINTNEXTLINE(cppcoreguidelines-no-malloc)
    free(NewElts);
    return NewEltsReplace;
}
}  // namespace

// Note: Moving this function into the header may cause performance regression.
template <class Size_T>
void* SmallVectorBase<Size_T>::mallocForGrow(void* FirstEl, size_t MinSize, size_t TSize, size_t& NewCapacity) {
    NewCapacity = getNewCapacity<Size_T>(MinSize, TSize, this->capacity());
    // Even if capacity is not 0 now, if the vector was originally created with
    // capacity 0, it's possible for the malloc to return FirstEl.
    void* NewElts = safe_malloc(NewCapacity * TSize);
    if (NewElts == FirstEl) {
        NewElts = replaceAllocation(NewElts, TSize, NewCapacity);
    }
    return NewElts;
}

// Note: Moving this function into the header may cause performance regression.
template <class Size_T>
void SmallVectorBase<Size_T>::grow_pod(void* FirstEl, size_t MinSize, size_t TSize) {
    size_t NewCapacity = getNewCapacity<Size_T>(MinSize, TSize, this->capacity());
    void* NewElts;
    if (BeginX == FirstEl) {
        NewElts = safe_malloc(NewCapacity * TSize);
        if (NewElts == FirstEl) {
            NewElts = replaceAllocation(NewElts, TSize, NewCapacity);
        }

        // Copy the elements over.  No need to run dtors on PODs.
        memcpy(NewElts, this->BeginX, size() * TSize);
    } else {
        // If this wasn't grown from the inline copy, grow the allocated space.
        NewElts = safe_realloc(this->BeginX, NewCapacity * TSize);
        if (NewElts == FirstEl) {
            NewElts = replaceAllocation(NewElts, TSize, NewCapacity, size());
        }
    }

    this->set_allocation_range(NewElts, NewCapacity);
}

template class ttsl::detail::llvm::SmallVectorBase<uint32_t>;

// Disable the uint64_t instantiation for 32-bit builds.
// Both uint32_t and uint64_t instantiations are needed for 64-bit builds.
// This instantiation will never be used in 32-bit builds, and will cause
// warnings when sizeof(Size_T) > sizeof(size_t).
#if SIZE_MAX > UINT32_MAX
template class ttsl::detail::llvm::SmallVectorBase<uint64_t>;

// Assertions to ensure this #if stays in sync with SmallVectorSizeType.
static_assert(
    sizeof(SmallVectorSizeType<char>) == sizeof(uint64_t), "Expected SmallVectorBase<uint64_t> variant to be in use.");
#else
static_assert(
    sizeof(SmallVectorSizeType<char>) == sizeof(uint32_t), "Expected SmallVectorBase<uint32_t> variant to be in use.");
#endif
